S10 V8 Swap: Project Sten - Part V

Perhaps I should start this installment of Project Sten with a confession. The idea of a cheap, V8-powered S-10 pickup sounded great. But once I got into it, we ran into multiple issues/dilemmas/snafus all of my own making. First was the choice of a TPI engine. I thought this standard small-block route would be less expensive than a used 4.8L or 5.3L LS truck engine. That decision wasn't necessarily wrong, but the cheap part of this project has completely vaporized in a cloud of essential emission and small parts that were accompanied by an oversized price. It wasn't the individual cost as much as when you add it all up; these little parts accounted for a substantial hit. My biggest blunder was not purchasing a complete, used TPI engine with the wiring harness and computer. Instead, because I already had a TPI manifold and a willing small-block, I had what I thought was most of what I needed. That's when all those essential small parts began to wag their fingers at me. Worse yet, because we live in the People's Republic of California, where the state awards Prius drivers with green laurels to wear on their heads when they drive, we had to build this truck to meet the existing smog rules for a '90 305 Camaro, which is the engine we were claiming was sitting between the framerails. I didn't take into account the rather complex smog component arrangement used on a speed-density TPI Camaro. But that was only the beginning.

Good intentions and enthusiasm always follow the purchase of a new project. The key to a successful project is maintaining that enthusiasm over the long haul. It may sound strange, but right out of the gate, I'll admit that I really didn't want to rip into this little S-10 truck. After purchase, the little four-banger S-10 immediately rewarded me with 22 mpg, so it was difficult to go back to a 15-mpg fullsize truck when driving a minimum of 70 commuter-miles a day. So I drove Sten for almost a year before the project could wait no longer.

All was going well until we got to the engine buildup that ran in the Oct. '11 issue. Work was progressing slowly, but we stuffed the engine and transmission in the truck and were forging ahead. That's until Car Craft reader Dennis Adams, a GM technician and accredited California smog inspector, commented that the engine couldn't be smog-legal because the heads on Sten's engine were not equipped with exhaust cross-overs. The factory TPI exhaust gas recirculation (EGR) valve uses this exhaust cross-over as the source for exhaust gas, so clearly Dennis was correct. I screwed up. I quickly reorganized and pulled a dusty pair of used late-'80s heads from under the bench that had the magic combination of both exhaust cross-overs and the centerbolt valve cover pattern. After rebuilding the heads with new guides and springs, I torqued them in place on the engine only to discover these castings used the vertical intake manifold bolt angle on the center four intake manifold bolt holes, and the stock TPI manifold pattern didn't match. After more gnashing of teeth and cursing that would make a Marine drill sergeant proud, I purchased a pair of Dart iron heads with the correct exhaust cross-over and fitted them with new valves and Comp beehive springs just to get back to where we had been about four months prior. This is just one reason why this project has taken longer and why starting with a complete TPI engine would have saved me all kinds of time and grief.

Then we decided to tackle the most challenging part of the buildup, which was the part that I held the least enthusiasm for completing—the wiring. I found a company called Bluestar Wiring Diagrams on the web that sold me a schematic of my four-cylinder S-10 that we used to mark each connector to the engine and compartment. Then we had to decide on which ones to keep, such as the starter circuit, power to the interior, and the alternator charging circuit. At least with the alternator, we got lucky since our 350 used the same CS130 alternator, so the charging system was a simple plug and go. We trimmed all the old four-cylinder wiring and then began routing the new Painless harness. This was slightly easier since '90 305 and 350 engines were speed-density controlled and did not use a mass airflow sensor (MAF) sensor.

While the Painless harness looks intimidating, it was one of the easiest things to make work. The work entailed routing the wiring to make the engine compartment look presentable and routing the main harness through the body, while keeping away from the passenger-side exhaust manifold. We also used a slick Earl's firewall grommet to minimize heat intrusion into the passenger compartment.

Tim Moore did a fantastic job of routing the exhaust work down from the cast-iron manifolds to the California-legal catalytic converter from Summit Racing. At first, we were going to plumb the tailpipe all the way to the rear, but then Tim suggested pushing the tailpipe over the framerail and exiting the exhaust through the box on the passenger side. The cut in the body is perfect—we'll finish that effort with a stainless steel bezel at a later date. With our new Optima battery relocated to the bed and a new Powermaster starter in place, we were ready to fire this rascal.

After all this work, it was a bit of a shock when the engine finally fired. Of course, we had to first repair a shorted wiring harness when we accidentally squeezed an injector hot lead to a direct short under the fuel rail. But once we overcame that hurdle, the engine fired right up. We still had a few emission harness connections to complete, which was why the check-engine light on the Painless harness illuminated, but these will be easy fixes once the connections are made. The hydraulic clutch also gave us trouble, until Mike Knell suggested a fix he remembered reading about in a Chevy service bulletin. We compressed the hydraulic plunger, and the system worked. We're still not sure exactly how this works, but it did.

The most recent hiccup was the throttle linkage. We found what we thought was the correct TPI Camaro throttle cable (that is now discontinued) only to discover it didn't match our throttle body. We had an ACCEL 1,000-cfm throttle body that worked with the cable, but it isn't California emissions legal, so we contacted TPIS, and the company is sending us a stock but larger 52mm throttle body (up from 48mm) that will work along with one of TPIS's airfoils.

Once we hit the street on our first couple of test drives, the truck ran fine. The latest swap was to add a power-steering box to the truck. The truck had been originally equipped with manual steering, but we discovered that Summit Racing offers a rebuilt version of the '88 Monte Carlo SS steering box for a budget price, so we popped for one and a new rag joint, as well as a new power-steering hose, also from RockAuto. After bleeding the power-steering system, it worked like a champ, and now we have a very quick 2.5 turn lock-to-lock steering box for our planned autocross assault.

Our next adventure will be to submit our humble Sten to a California Bureau of Automotive Repair (BAR) Referee to inspect our emissions equipment work and either boot us to the street to try again, or bless our work with a pat on the back and the necessary paperwork to allow us to register the S-10 as an emissions-legal V8 swap. Next, we have a very cool idea for a rearend swap that you will want to read. It's both inexpensive, a great idea, and plenty durable, too. So stay tuned.

Parts List

Description

PN

Source

Price

Camaro Y-pipe

40579

Summit Racing

$88.97

Camaro catalytic converter

80544

Summit Racing

185.97

Summit V-band clamps

694300 (2)

Summit Racing

36.97 ea.

Dart SBC heads, bare

10021070

Summit Racing

553.62 (pr.)

Summit 1.50 exhaust valves

V8008-8

Summit Racing

64.97

Summit 1.94 intake valves

V8000-8

Summit Racing

64.97

Comp beehive valvesprings

26915

Summit Racing

192.97

Painless engine harness

60103

Summit Racing

426.97

Earl's Firewall grommet

29G008ERL

Summit Racing

28.97

Flowmaster muffler, 3-inch

943050

Summit Racing

101.99

Flowmaster pipe kit

15902

Summit Racing

89.99

Powermaster starter

9100

Summit Racing

124.97

Optima battery

9004-003

Summit Racing

179.97

Steering box, '88 Monte SS

27-6550

Summit Racing

119.97

Vapor can purge connector

PT245

RockAuto

11.09

Diverter valve conn. (green)

PT248

RockAuto

14.74

Diverter valve conn. (white)

PT249

RockAuto

15.84

Knock sensor

42062

RockAuto

25.79

Fuel pump relay

212307

RockAuto

13.07

Power-steering hose

357190

RockAuto

22.79

GM, F-car throttle cable

10163822

Weseloh Chev.

27.00

Lower radiator hose T-fitting

See website

Stealth Conver.

25.00

Heater hose restrictor

HHR1

Stealth Conver.

10.00

TPIS 52mm throttle body

1.TB151

TPIS

279.95

S-10 V8 conversion manifold

JTR-S10

Summit Racing

28.99

Back Stories
Project Sten has been languishing on the back burner way too long. To refresh your memory, we've included the previous installments. As you can see by the article dates, the first thing we had to do was blow the dust off Project Sten.

Installment

Issue Date

Description

Project Sten, Part I

Mar. 2011

Project goals, purchase truck

Project Sten, Part II

Oct. 2011

350ci TPI engine build

Project Sten, Part III

Nov. 2012

Engine, trans, clutch, cooling

Project Sten, Part IV

Dec. 2012

Seats, wiring, and hydraulic clutch

Junkyard Builder

Mar. 2013

Fuel pump upgrade

2/13It’s been a few months since Sten has made an appearance in Car Craft, but we’re back and running—finally!

3/13Notice we have one head with a heat cross-over and one without. This was attempt No. 1, before I realized that the head with the cross-over used the obscure small-block center intake bolt pattern that doesn’t match the TPI manifold. Arrrrgghh!

4/13These are the new 180cc intake port Dart heads with heat cross-over that finally found their way onto the engine as the now final version of our TPI engine. Somewhere, S-10 engine-swap book author Mike Knell is thinking, I told you, but you didn’t listen!

5/13My friend, Bill Irwin, from Iowa helped me integrate the new Painless engine harness with the existing S-10 harness. The TPIS-tuned ECU will reside behind the glovebox inside the interior. An important step is to connect the constant 12-volt alternator power lead to the insulated terminal on the firewall through to the starter motor. Then we had to create a separate switched 12v power terminal under the hood.

6/13Once the engine was ready to run, I took Sten to Tim Moore’s shop for some custom exhaust work. It is very tight between the S-10 passenger framerail and the exhaust, which required Moore to make multiple cuts to create a Y-pipe from a combination of a stock 5.0L ’90 Camaro and 4.3L S-10 V6 Y-pipes. The new Camaro Y-pipe came from Summit Racing, while the 4.3L one was found at the junkyard.

7/13Constructing the Y-pipe required significant welding and pipe maneuvering mainly on the passenger side to squeeze the pipe inside the framerail. There were four segments just between the passenger-side exhaust manifold and the Y junction.

8/13

9/13Moore welded our California-legal Walker catalytic converter obtained from Summit Racing and then used Summit 3-inch stainless V-band clamps. Then Moore added a single Flowmaster 3-inch muffler that he routed above the frame and cut a hole in the truck’s box for a very cool side outlet. Later, we’ll add a stainless steel bezel with stainless fasteners.

10/13After removing and replacing the intake about six or seven times, we managed to pinch this power wire between the fuel rail and the manifold. We discovered very quickly that these wires are hot anytime the key is on—but only after we barely avoided melting a major portion of the entire engine harness! The message here is work carefully when installing the TPI manifold.

11/13It’s difficult to see, but there’s smoke coming off the exhaust manifolds just after we fired the engine for the first time. Bill is adjusting the throttle-body idle stop.

12/13Supplying both the electrical power and the torque to get our package started is an Optima Red Top, dual-terminal battery and a Powermaster PowerMAX permanent magnet, gear reduction (PMGR) starter. Powermaster recently upgraded these starters with steel gears. For more about PMGR starters, check out the July ’12 Junkyard Builder.

13/13We also bolted in an ’88 Monte Carlo SS steering box into the S-10, along with a Gates power-steering hose. We had to use a metric Saginaw return side adapter fitting that we obtained from DMP Fasteners, but this was the only trick part we had to use.